Roll head



W. E. BOUR Oct. 16, 1962 ROLL HEAD 5 Sheets-Sheet l a v I Filed March 9.1959 Rm M0 N9 E m M m L H W ML. llfil i Oct. 16, 1962 Filed March 9.1959 W. E. BOUR ROLL HEAD 3 SheetsSheet 2 i r- Hm. I 9 u.

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FIG.6

FIGS

, INVENTOR.

WILLIAM (E. BO R has The invention relates in general to variablediameter roll heads and more particularly to a roll head capable of coldworking a workpiece to form threads of diiferent diameters on theworkpiece.

Thread rolling heads have been used in the past for machine threads ofconstant diameter and have proved their superiority over cut threads inquality of finish and speed of production.

An object of the invention is to provide a thread rolling head whichwill produce variable diameter threads such as tapered pipe threads.

Another object of the invention is to provide a roll head with rolls forcold working a workpiece to deform the metal of the workpiece in avariable diameter as the working progresses axially.

Another object of the invention is to provide a roll head wherein thethread rolls are controlled in movement by a profile cam which canchange the diameter of the workpiece as the threading progresses.

Another object of the invention is to provide a roll head wherein threadrolls move outwardly slowly to produce a tapered thread and then moveout rapidly to provide a rapid opening action of the roll head.

Another object of the invention is to provide a roll head with a clutchto provide a tapering retractile movement of the thread forming meansand also to provide a rapid retractile or collapsing movement of thethread forming means.

Another object of the invention is to provide a thread rolling head toroll tapered or changing diameter threads on either solid or hollowworkpieces.

Another object of the invention is to provide a method of forming taperthreads on a hollow workpiece.

Another object of the invention is to provide a method wherein a taperthread is rolled on a hollow workpiece during axial advancing movementand; subsequently, the hollow workpiece is drilled to a cylindricalinternal surface during the retractile movement.

Another object of the invention is to provide a thread roll head with adrill which enters a hollow workpiece and then the head axially forms ataper thread on the external surface of the hollow workpiece andsimultaneously crushes or deforms the workpiece to a tapered internalbore and then on the retracting movement the drill drills the hollowworkpiece to a cylindrical bore.

Other objects and a fuller understanding of this invention may be had byreferring to the following description and claims, taken in conjunctionwith the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view of a roll head in accordancewith the invention.

FIGURE 2 is a front view of the head of FIGURE 1.

FIGURE 3 is a side elevational view of the dog clutch on the roll head.

FIGURE 4 is a rear elevational view of the dog clutch of FIGURE 3.

FIGURE 5 is a developed view of the clutch surface of FIGURE 4.

FIGURE 6 is a fragmentary view of the dog clutch and frame showing theadjustment calibration.

FIGURE 7 is a longitudinal sectional view of the clutch collar.

FIGURE 8 is a front elevational view of the clutch collar.

3,058,196 Patented Oct. 16, 1962 FIGURE 9 is a developed view of theclutch surface of FIGURE 8.

FIGURE 10 is a longitudinal sectional view of a modified roll head.

FIGURE 11 is a front elevational view of the roll head of FIGURE 10.

FIGURE 12 is a fragmentary view of the workpiece during the threadrolling operation and;

FIGURE 13 is a fragmentary view of the workpiece after completion of thethread forming operation.

FIGURES 1 and 2 show a roll head 15 shown as a taper roll head and whichincludes generally a shank 16 having an axis 17 and a frame 18 coaxialwith the shank 16. The frame includes generally a front and rear plates21 and 22 and a spring housing 23. A plurality of headed bolts 26adjustably fasten together the rear plate 22. and the spring housing 23with the bolts 26 passing through arcuate slots 27 in the spring housingfor this adjustment purpose. Cap screws 28 fasten the front plate 21into the heads of the bolts 26 so as to fasten together the variousparts of the frame 18.

A plurality of rolls act on the workpiece such as two or three rolls,and FIGURES 1 and 2 show three thread rolls 31 cold working a workpiece32 to form a thread thereon. The workpiece 32 has been shown as a solidpipe plug on which tapered threads have been formed by the roll head 15.

The thread rolls 31 are journalled on roller bearings 33 on eccentricportions 34 of shafts 35. These shafts are journalled in the front andrear plates 21 and 22 for arcuate movement. The shafts 35 are skewed ata slight angle so that the cold working surface on the thread rolls 31is in the form of annular grooves rather than a true thread. Each shaft35 carries a pinion 36 and all pinions mesh with a central spur gear 37which has a hub 38 journalling the second plate 22 and this gear in turnis splined to the shank 16 at 39'. This gearing provides that when thecenter gear 37 rotates relative to the rear plate 22, the pinions 36will rotate to rotate the shafts 35 and move the eccentrics 34 so thatthe thread rolls 31 are moved toward or away from the axis 17.

A torsion spring 41 interconnects the spring housing 23 and the shank 16and urges the frame 18 in a first rotational direction relative to theshank which rotational direction is the same as the direction of rollingthe particular thread onto a workpiece. For the right hand threadsshown, this is a clockwise movement of the frame as viewed from the rearend of the roll head 15. A dog clutch includes a first clutch part '42on the spring housing 23 and a second clutch part 43 on a collar 44. Thecollar 44 is coaxial on the shank 16 and is slideably mounted thereonbut is prevented from relative rotation therewith by a transverse bar 45having a threaded end 46 engaging the collar and locked by a lock nut47. The transverse bar 45 passes through a central shaft 50 which isurged toward the front of the roll head 15 by an axial compressionspring 51 so that the entire collar 44 is urged axially forwardly.

The first clutch part 42 on the spring housing 23 has first matingsurfaces 52, see FIGURES 3 to 9, and the second clutch part 43 hassecond mating surfaces 53. These mating surfaces may mutually engage andthe mating surfaces are long in an axial direction and the second matingsurfaces 53 are axially tapering in the first rotational direction. Asshown in FIGURE 1 the axial spring 51 axially urges together the clutchparts 42 and 43, and the torsion spring 41 rotationally urges togetherthe mating surfaces 52 and 53. The first and second clutch parts arealso provided with arcuate stop surfaces 54 which come into mutualengagement'when the clutch parts have been separated axiallysufficiently clutch parts 42 and 43. This arcuate movement has beenshown as being about 60 degrees and during this movement the threadrolls 31 rapidly move away from the axis 17 to effect an openingmovement of the roll head 15. During the axial separation movement ofthe clutch parts 42 and 43, the mating surfaces 52 and 53 are urged intoengagement by thetorsion spring 41 and during this axial movement thereis a slight relative rotational movement of the clutch parts because ofthe tapered mating surface 53. This slight rotational movement of theframe 18 relative to the shank 16 rotates the pinions 36 slightly togradually move the thread rolls 31 outwardly. This forms a taper threadon the workpiece 32 as the workpiece and roll head are relativelyaxially advanced.

The axial separation of the clutch parts 42 and 43 in accordance withthe relative axial advancing movement of the workpiece and roll head iseffected by a work stop 55. This work stop 55 is loosely held on theshaft 50 by a bolt 56 and acts on this shaft through a thrust bearing57. Thus as the workpiece 32 and the roll head 15 axially advance, thework stop 55 abuts the workpiece 32 and, hence, there is relative axialmovement by the clutch parts 42 and 43 in accordance with this relativeaxial movement.

A disc 60 may be fastened to the collar 44 by the bolts 61 and this disc60 may be engaged by a yoke, not shown, which is axially stationaryrelative to the workpiece 32. When this disc 60 is used the work stop 55need not be provided since action of the yoke against disc 60 willprovide for relative axial movement of the clutch parts 42 and 43 inaccordance with the relative axial movement of the workpiece 32 and rollhead '15.

Operation The roll head 15 may be used in either stationary or rotatingapplications and in either application the roll head may be axiallystationary or movable. The roll head 15 may thus be used in any one offour different modes of operation as long as there is relative axialmovement between the roll head 15 and workpiece 32 as well as relativerotational movement. As the roll head 15 is used in an applicationwherein the head itself rotates and the blank workpiece 32 is fedaxially into the roll head, then the workpiece moves into the spacebetween the thread rolls 31 and contacts the work stop 55 approximatelyat the same time that the thread rolls 31 begin operation on the blankworkpiece. The first one or two threads on the thread rolls 31 arechamfered so as to facilitate the beginning of the thread rollingoperation. As the workpiece 32 feeds axially into the thread rolls 31the work stop 55 moves the collar 44 backwardly against the urging ofthe coil spring 51. This means that the first and second clutch parts 42and 43 begin to axially separate and because the mating surface 53 istapered the spring housing 23 commences to rotate clockwise, as viewedfrom the rear, relative to the shank 16. In FIG- URE 2, this means thatthe frame 18 is rotating counterclockwise and; hence, the pinions 36roll on the center gear 37 so that the shafts 35 turn counter-clockwiserelative to the frame 18. This moves the centers of the eccentrics 34gradually outwardly away from the axis 17 and; therefore, a taper threadis formed on the workpiece 3-2 during the axial movement wherein themating surfaces 52 and 53 are in engagement. If the mating surface 53 ismade other than a straight surface, as shown in the developed viewthereof, the taper thread will be changed to a sloping or variablediameter surface directly in accordance therewith.

The length of the mating surface 53 is preferably made proportional tothe length of the taper thread desired on the workpiece 32, and at theend of the thread rolling operation the dog clutch 42-43 has beenaxially separated sufficiently so that a rapid arcuate movement takesplace under urging of the torsion spring 41. This rotates the fastenedto the drill 70 by set screws 75.

frame 18 relative to the shank 16 through an arc of about 6t) degrees,as shown in FIGURES 3-9, until the arcuate stop surfaces 54 come intoengagement. This is a rapid opening movement of the roll head so thatthe thread rolls 3-1 rapidly move away from the axis 17 so that theworkpiece 32 and roll head 15 may be axially separated in a retractingmovement without unthreading these two parts.

As the mating surfaces 52 and 53 are changed in surface contour, theamount of taper on the workpiece 32 will change accordingly and themating surface 53 may be changed to slope even in the reverse rotationaldirection, if desired, to form a gradually decreasing diameter on theworkpiece rather than gradually increasing diameter.

The roll head 15 may easily be reclosed ready for another thread rollingoperation. This reclosing action is performed by relative rotationalmovement of the frame 18 and shank 16 in a second or reverse rotationaldirection. Viewing FIGURE 2, this is a clockwise rotational movement ofthe frame 18 relative to the shank 16, for right hand threads. When thehead 15 is used in rotatively stationary applications, this closing mayreadily be accomplished by the operator grasping and rotating the frame18, or a handle fastened thereto. For rotating head applications,therhead may be closed by applying a braking force to some part of theframe 18, such as a pinch brake on the outer periphery thereof, becausethe second rotational direction is opposite to the first or threadrolling rotational direction. Inertia closing may also be used forrotating applications, and relies on the mass of the frame 18. In thismethod, the spindle chucking and driving the shank 16 is momentarilyslowed and then reaccelerated, and during such acceleration the inertiaof the frame 18 causes it to accelerate not as rapidly, hence the shankmoves more quickly in the first rotational direction to close the clutch4243. In all these closing actions, once the clutch parts 42 and 43 havebeen rotated sufiiciently in the second rotational direction so that themating surfaces 52 and 53 are aligned, the axial urging of the spring 51will effect axial closing of the clutch.

The mating surface 53 is shown as a tapered surface, but more broadlymay be considered a profile cam controlling the movement of the threadrolls. If this mating surface is changed from a taper to one having twoaxially parallel portions with a step therebetween, then the threadrolls will roll a workpiece with a thread having a constant diameteruntil the step is reached, whereupon the workpiece diameter will bechanged and a second part of the workpiece thread will be rolled at adifferent diameter, which may be either larger or smaller. Also, onepart of the profile cam may be axially parallel and another part taperedor of any other desired shape, so that the threaded workpiece will havea shape as dictated by this profile cam 53.

FIGURES 10 and 11 show a modified form of the invention wherein the rollhead 15A is adapted primarily for forming threads on the externalsurface of a workpiece 32A. In this modification the work stop 55 isremoved and instead a central drill 70 is provided. This drill isthreaded into a sleeve 71 which is fastened by a cross pin 72 to acentral shaft 73. A chamfer tool 74 is The central shaft 73 is fastenedto the shank 16 by a set screw 76 threaded in the shank 16 andbearingagainst a fiat on the shaft 73. Thus the drill 70 is rotativelystationary relative to the shank 16.

A compression spring 78 is mounted in a recess 79in the shaft 73 andurges forwardly the sleeve 71 and drill 70 so that the cross pin 72 isat the forward end of an elongated slot 80 in the shaft 73. A stop 81for the axial spring 51 is centrally apertured and tapped at $2 to beconnected to a coolant supply. Coolant is furnished through a coolantconduit 83 to a central bore 84 in the shaft 73 and a central bore 85 isthe drill 70. The coolant may emerge from an exit 86 to act upon theworkpiece 32A. Because the drill 70 and chamfer tool 74 produce chips,the front plate 21A has been provided with an enlarged three lobedaperture 87 for easy egress of these chips.

The axial compression spring 51 acts against a thrust washer 89 againstend of cross pins 90 fastened in the collar 44. By this means the clutch4243 is axially urged into engagement.

Operation The roll head 15A is designed to be used with a hollowworkpiece 32A such as metal pipe and to roll taper threads on suchworkpiece. The drill 70 extends forwardly of the front plate 21A so thatit enters the internal bore of the hollow workpiece before the externalsurface of the workpiece engages the thread rolls 31. The drill '74} ischosen of a size that enters the workpiece without actually removing anymetal therefrom during the advancing movement into the pipe workpiece32A. As the thread rolls 31 engage the external surface of the workpiece32A during relative axial advancing movement, the action of the rollscrushes or deforms the workpiece to a smaller internal bore. Again thefirst one or two threads of the thread rolls are preferably chamfered toaid in the commencement of the thread roll action. As the thread rollingcommences the clutch parts 42 and 43 are relatively axially separated inany desired manner. This may be accomplished by a yoke 93 which isaxially fixed relative to the workpiece 32A and which has rollers 94hearing on the disc 60. By this means the collar 44 moves backwardly asthe workpiece 32A enters the space between the thread rolls 31. Themating surfaces 52 and 53 of FIGURES 3-9 cause gradual relativerotational movement of the frame 18 and the shank 16 so that the threadrolls 31 are gradually moved away from the aXis 17. This produces thetaper thread on the external surface of the workpiece 32A. Initially theblank pipe workpiece 32A is as shown in FIGURE with substantiallycylindrical internal and external surfaces. After the thread rollingoperation, when the end of the pipe is at the chamfer tool 74, theworkpiece 32A appears as shown in FIG URE 12. Because of the threadrolling action, as opposed to a thread cutting action, the wallthickness 95 from the internal surface 96 to the pitch line 97 remainssubstantially the same as before the threading action on the workpiece.Also the internal surface 96 now has a tapered internal boresubstantially parallel to the taper on the pitch line 97. This is due tothe crushing or deforming action of the thread rolls 31 on the hollowworkpiece. The drill 70 has likewise been advancing farther into theworkpiece 32A so that it is forward of the tapered surface 96 and in asubstantially nondeformed portion of the workpiece.

At the completion of the thread rollin-g action the chamfer tool 74chamfers both inside and outside edges of the end of the workpiece 32A.Next the mating surfaces 52 and 53 become axially disengaged and thetorsion spring 41 rotates the frame 18 in a forward rotational directionrelative to the shank 16 until the arcuate stop surfaces 54 engage. Thisis the rapid opening action of the rolling head. Next the workpiece 32Aand roll head A are relatively retracted. During this retractingmovement the drill 70 cuts the internal surface of the workpiece 32A.For this purpose the drill 70 has a reverse cutting edge 98 which has asmaller diameter nearer the shank of the drill than at the forward endof the drill. This cutting action of the drill or reamer 70 cuts a newinternal surface 99, as shown in FIGURE 13, which is the same diameteras the drill 70 and preferably is the same diameter as the originalinternal diameter of the pipe workpiece 32A. By this action the pipe istaper threaded, chamfered, and rebored to its original diameter, allwith a single advancing and retracting cycle of operation. By

this means much greater productive capacity is achieved for this rollhead 15A because the taper threads may rapidly be rolled on theworkpiece and then the drill 70 returns the internal bore to itsoriginal condition during the retracting movement.

Although this invention has been described in its preferred form with acertain degree of particularity, it is understood that the presentdisclosure of the preferred form has been made only by way of exampleand that numerous changes in the details of construction and thecombination and arrangement of parts may be resorted to withoutdeparting from the spirit and the scope of the invention as hereinafterclaimed.

What is claimed is:

l. A variable diameter roll head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, working rolls carried on said head, a dog clutchincluding first and second clutch parts, first and second matingsurfaces on said first and second clutch parts, respectively, a profilecam surface other than axially parallel on one of said mating surfaces,means connecting said clutch parts to said working rolls to effectmovement of said rolls relative to said axis upon relative rotationalmovement of said clutch parts, spring means connected to axially urgetogether said clutch parts and to rotatively urge together said matingsurfaces, and means to relatively axially separate said clutch parts asa workpiece and said head are relatively axially advanced to cold worksaid workpiece, whereby the profile cam surface and said spring meansestablish relative arcuate movement of said clutch parts to move saidworking rolls relative to the axis of said rolling head to form avariable diameter external surface on said workpiece.

2. A cold working head having an axis, comprising, in combination, ashank adapted for mounting in a suport and disposed coaxially on saidaxis, a frame on said shank, eccentrics on said frame, working rollsjournalled on said eccentrics, a collar on said shank, a dog clutchincluding a first clutch part on said frame and a second clutch part onsaid collar, first and second mating surfaces on said first and secondclutch parts, respectively, holding said frame against rotation in afirst rotational direction, a profile cam surface other than axiallyparallel on one of said mating surfaces, means connecting said clutchparts to said eccentrics to effect arcuate movement of said eccentricsrelative to said frame upon relative rotational movement of said clutchparts, spring means connected to axially urge together said clutch partsand to rotatively urge together said mating surfaces, and means torelatively axially separate said clutch parts as a workpiece and saidframe are relatively axially advanced to cold work said workpiece,whereby the profile cam surface and said spring means establish relativearcuate movement of said clutch parts to move said working rollstransversely relative to the axis of said head to form a variablediameter external surface on said workpiece.

3. A taper thread rolling head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, a frame coaxial on said shank, shafts journalledon said frame, an eccentric on each shaft, thread rolls journalled onsaid eccentrics, a collar on said shank, a dog clutch including a firstclutch part on said frame and a second clutch part on said collar, oneof said clutch parts being axially movable, first and second matingsurfaces on said first and second clutch parts, respectively, springmeans connected to relatively axially and rotatively urge said matingsurfaces together, an axially tapered surface on one of said matingsurfaces tapering in a first rotational direction to establish relativerotation between said clutch parts upon relative axial movement thereof,means connecting said clutch parts to said eccentrics to efiect rotationthereof upon relative rotational movement of said clutch parts,

means to relatively axially separate said clutch parts as a workpieceand said frame are relatively axially advanced to roll a thread on saidworkpiece, whereby said tapered surface and said spring means establishrotation of said eccentrics to move said thread rolls transversely awayfrom the axis of said rolling head to form a tapered thread on saidworkpiece, and arcuate stop means on said first and second clutch partsto establish an arcuate stop for said first and second clutch partsafter sufficient axial separation thereof has caused said first andsecond mating surfaces to become disengaged and said spring means hascaused rapid relative arcuate movement of said clutch parts to effect arapid opening of said thread rolls.

4. A taper thread rolling head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, a frame caxial on said shank, shafts journalledon said frame, an eccentric on each shaft, thread rolls journalled onsaid eccentrics, a pinion on each shaft, a spur gear meshing with saidpinions, a collar on said shank, a dog clutch including a first clutchpart on said frame and a second clutch part on said collar, one of saidclutch parts being axially movable, first and second mating surfaces onsaid first and second clutch parts, respectively, spring means connectedto relatively axially and rotatively urge said mating surfaces together,an axially tapered surface on one of said mating surfaces tapering in afirst rotational direction to establish relative rotation between saidclutch parts upon relative axial movement thereof, means connecting saidclutch parts to said pinions and spur gear to effect rotation of saidpinions relative to said spur gear upon relative rotational movement ofsaid clutch parts, means to relatively axially separate said clutchparts as a workpiece and said frame are relatively axially advanced toroll a thread on said workpiece, whereby said tapered surface and saidspring means establish rotation of said pinions relative to said frameto move said thread rolls transversely away from the axis of saidrolling head to form a tapered thread on said workpiece, and arcuatestop means on said first and second clutch parts to establish an arcuatestop for said first and second clutch parts after sutficient axialseparation thereof has caused said first and second mating surfaces tobecome disengaged and said spring means has caused rapid arcuaterelative movement of said clutch parts to effect a rapid opening of saidthread rolls.

5. A taper thread rolling head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, a frame including first and second platescoaxial on said shank, shafts journalled on said frame between saidplates, an eccentric on each shaft between said plates, thread rollsjournalled on said eccentrics, a pinion on each shaft, a spur gearmeshing with said pinions and splined to said shank, a hub on said spurgear journalling said frame on said shank, spring means connectedbetween said shank and said frame to urge said frame in a firstrotational direction relative to said shank, a collar non-rotativelyattached on said shank, a dog clutch including a first clutch part onsaid frame and a second clutch part on said collar, one of said clutchparts being axially movable, first and second mating surfaces on saidfirst and second clutch parts, respectively, holding said frame againstrotation in said first rotational direction, said spring means acting toaxially urge together said clutch parts, an axially tapered surface onsaid second mating surface tapering in said first rotational direction,means to relatively axially separate said clutch parts as a workpieceand said frame are relatively axially advanced to roll a thread on saidworkpiece, whereby the tapered surface and said spring means establisharcuate movement of said frame in said first rotational directionrelative to said shank to move said thread rolls transversely away fromthe axis of said rolling head to form a tapered thread on saidworkpiece, and arcuate stop means on said first and second clutch partsto establish an arcuate stop for said first and second clutch partsafter sufiicient axial separation thereof has caused said first andsecond mating surfaces to become disengaged and said spring means hascaused rapid arcuate movement of said frame to effect a rapid opening ofsaid thread rolls.

6. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis, a frame including first and secondplates coaxial on said shank, skewed shafts on said frame between saidplates, an eccentric on each shaft between said plates, thread rollsjonrnalled on said eccentrics, a pinion on each shaft, a spur gearmeshing with said pinions, a spring housing as part of said frame andarcuately adjustably fastened to said second plate, a collar on saidshank, a dog clutch including a first clutch part on said frame and asecond clutch part on said collar, one of said clutch parts beingaxially movable, first and second mating surfaces on said first andsecond clutch parts, respectively, a torsion spring connected torelatively urge said mating surfaces together, a coil spring in saidshank acting to axially urge together said clutch parts, an axiallytapered surface on said second mating surface tapering in a firstrotational direction to establesh relative rotation between said clutchparts upon relative axial movement thereof, means connecting said clutchparts to said pinions and spur gear to effect rotation of said pinionsrelative to said spur gear upon relative rotational movement of saidclutch parts, means to relatively axially separate said clutch parts asa workpiece and said frame are relatively axially advanced to roll athread on said workpiece, whereby said tapered surface and said torsionspring establish rotation of said pinions relative to said frame to movesaid thread rolls transversely away from the axis of said rolling headto form a tapered thread on said workpiece, and arcuate stop means onsaid first and second clutch parts to establish an arcuate stop for saidfirst and second clutch parts after sufficient axial separation thereofhas caused said first and second mating surfaces to become disengagedand said torsion spring has caused rapid arcuate relative movement ofsaid clutch parts to effect a rapid opening of said thread rolls.

7. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis, a frame including first and secondplates coaxial on said shank, skewed shafts journalled on said framebetween said plates, an eccentric on each shaft between said plates,thread rolls journalled on said eccentrics, a pinion on each shaft, aspur gear meshing with said pinions and splined to said shank, a hub onsaid spur gear journalling said frame on said shank, a spring housing aspart of said frame and arcuately adjustably fastened to said secondplate, a torsion spring connected between said shank and said springhousing to urge said frame in a first rotational direction relative tosaid shank, a collar non-rotatively attached on said shank, a dog clutchincluding a first clutch part on said frame and a second clutch part onsaid collar, one of said clutch parts being axially movable, first andsecond mating surfaces on said first and second clutch parts,respectively, holding said frame against rotation in said firstrotational direction, a coil spring in said shank acting to axially urgetogether said clutch parts, an axially tapered surface on said secondmating surface tapering in said first rotational direction, means torelatively axially separate said clutch parts as a workpiece and saidframe are relatively axially advanced to roll a thread on saidworkpiece, whereby the tapered surface and said torsion spring establisharcuate movement of said frame in said first rotational directionrelative to said shank to move said thread rolls transversely away fromthe axis of said rolling head to form a tapered thread on saidworkpiece, and arcuate stop means on said first and second clutch partsto establish an arcuate stop for said first and second clutch partsafter sufficient separation thereof has caused said first and secondmating surfaces to become disengaged and said torsion spring has causedrapid arcuate movement of said frame to effect a rapid opening of saidthread rolls.

8. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis, a frame including first and secondplates coaxial on said shank, shafts journalled on said frame betweensaid plates, an eccentric on each shaft between said plates, threadrolls journalled on said eccentrics, a pinion on each shaft, a spur gearmeshing with said pinions and splined to said shank, a hub on said spurgear journalling said frame on said shank, a torsion spring connectedbetween said shank and said frame to urge said frame in a firstrotational direction relative to said shank, a collar axially slidableon said shank, a work stop axially slidable relative to said shank andaxially engageable with the end of a workpiece threadable between saidthread rolls, means to cause axial movement of said collar with saidwork stop, a closed rear end in said shank, a coil compression spring insaid shank between said closed end and said work stop urging said workstop to a position between said thread rolls, a dog clutch including afirst clutch part on said frame and a second clutch part on said collar,first and second mating surfaces on said first and second clutch parts,respectively, holding said frame against rotation in said firstroational direction by the urging of said torsion spring, one of saidfirst and second mating surfaces tapering in said first rotationaldirection, whereby as a workpiece is axially relatively advanced intothe space between said thread rolls to roll a thread thereon said workstop is engaged by said workpiece and moved rearwardly to move saidcollar and to gradually separate said clutch parts whereupon the taperedsurface and said torsion spring establish arcuate movement of said framein said first rotational direction relative to said shank to move saidthread rolls transversely away from the axis of said rolling head toform a tapered thread on said workpiece.

9. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis, a frame including first and secondplates coaxial on said shank, skewed shafts journalled on said framebetween said plates, an eccentric on each shaft between said plates,thread rolls journalled on said eccentrics, a pinion on each shaft, aspur gear meshing with said pinions and splined to said shank, a hub onsaid spur gear journalling said frame on said shank, a spring housing aspart of said frame and arcuately adjustably fastened to said secondplate, a torsion spring connected between said shank and said springhousing to urge said frame in a first rotational direction relative tosaid shank, a collar axially slidable on said shank, an axially parallelslot diametrically through said shank, a work stop axially slidablewithin said shank and axially engageable with the end of a workpiecethreadable between said thread rolls, a pin extending transverselythrough said slot and fixed in said work stop and in said collar tocause axial movement of said collar with said work stop, a closed rearend in said shank, a coil compression spring in said shank between saidclosed end and said work stop urging said work stop to a positionbetween said thread rolls, a dog clutch including a first clutch part onsaid spring housing and a second clutch part on said collar, first andsecond mating surfaces on said first and second clutch parts,respectively, holding said frame against rotation in said firstrotational direction by the urging of said torsion spring, an axiallytapered surface on said second mating surface tapering in said firstrotational direction, whereby as a workpiece is axially relativelyadvanced into the space between said thread rolls to roll a threadthereon said work stop is engaged by said workpiece and moved rearwardlyto move said collar and to gradually separate said clutch partswhereupon the tapered surface and said torsion spring establish arcuatemovement of said frame in said first rotational direction relative tosaid shank to move said thread rolls transversely away from the axis ofsaid rolling head to form a tapered thread on said workpiece, andarcuate stop means on said first andsecond clutch parts to establish anarcuate stop for said first and second clutch parts after suflicientaxial separation thereof has caused said first and second matingsurfaces to become disengaged and said torsion spring has caused rapidarcuate movement of said frame to effect a rapid opening of said threadrolls.

.10. A taper cold working head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, working rolls carried on said head, a dog clutchincluding first and second clutch parts, first and second matingsurfaces on said first and second clutch parts, respectively, an axiallyaligned .drill mounted to enter a workpiece before said working rollsact on the external surface of said workpiece, means connecting saiddrill rotatively fixed relative to said shank, an axially taperedsurface on one of said mating surfaces, means connecting said clutchparts to said working rolls to effect outward movement of said rollsrelative to said axis upon relative rotational movement of said clutchparts, spring means connected to axially urge together said clutch partsand to rotatively urge together said mating surfaces, means torelatively axially separate said clutch parts as a workpiece and saidhead are relatively axially advanced to cold work said workpiece,whereby the tapered surface and said spring means establish relativearcuate movement of said clutch parts to move said working rollsoutwardly away from the axis of said rolling head to form a taperedexternal surface on said workpiece, and said drill cutting the internalsurface of said workpiece cylindrical to the diameter of the drill assaid workpiece and said head are relatively axially retracted.

11. A taper cold working head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, a frame on said shank, eccentrics on said frame,working rolls journalled on said eccentrics, a collar on said shank, adog clutch including a first clutch part on said frame and a secondclutch part on said collar, first and second mating surfaces on saidfirst and second clutch parts, respectively, holding said frame againstrotation in a first rotational direction relative to said second clutchpart, an axially aligned drill mounted forward of said frame to enter ahollow workpiece before said working rolls act on the external surfaceof said workpiece, means connecting said drill rotatively fixed relativeto said shank, an axially tapered surface on one of said mating surfacestapering in said first rotational direction, means connecting saidclutch parts to said eccentrics to effect arcuate movement of saideccentrics relative to said frame upon relative rotational movement ofsaid clutch parts, spring means connected to axially urge together saidclutch parts and to rotatively urge together said mating surfaces, meansto relatively axially-separate said clutch parts as a workpiece and saidframe are relatively axially advanced to cold work said workpiece,whereby the tapered surface and said spring means establish relativearcuate movement of said clutch parts in said first rotational directionto move said working rolls transversely away from the axis of saidrolling head to form a tapered external surface on said workpiece, andsaid drill cutting the internal surface of said workpiece cylindrical tothe diameter of the drill as said workpiece and said frame arerelatively axially retracted.

12. A taper thread rolling head having an axis, comprising, incombination, a shank adapted for mounting in a support and disposedcoaxially on said axis, a frame coaxial on said shank, shaft journalledon said frame, an eccentric on each shaft, thread rolls journalled onsaid eccentrics, a pinion on each shaft, a spur gear meshing with saidpinions and fastened to said shank, spring means connected between saidshank and said frame to urge said frame in a first rotational directionrelative to said shank, a collar on said shank, a dog clutch including afirst clutch part on said frame and a second clutch part on said collar,first and second mating surfaces on said first and second clutch parts,respectively, holding said frame against rotation in said firstrotational direction, an axially aligned reverse cutting edge drillmounted to enter a hollow workpiece before said thread rolls act on theexternal surface of said workpiece, means connecting said drillrotatively fixed relative to said shank, said spring means acting toaxially urge together said clutch parts, an axially tapered surface onone of said mating surfaces tapering in said first rotational direction,means to relatively axially separate said clutch parts as a workpieceand said frame are relatively axially advanced to roll a thread on saidworkpiece, whereby the tapered surface and said spring means establisharcuate movement of said frame in said first rotational directionrelative to said shank to move said thread rolls transversely away fromthe axis of said rolling head to form a tapered thread on saidworkpiece, arcuate stop means on said first and second clutch parts toestablish an arcuate stop for said first and second clutch parts aftersufiicient axial separation thereof has caused said first and secondmating surfaces to become disengaged and said spring means has causedrapid arcuate movement of said frame to effect a rapid opening of saidthread rolls, and said drill cutting the internal diameter of saidworkpiece cylindrical to the diameter of the drill as said workpiece andsaid frame are relatively axially retracted.

13. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis, a frame including first and secondplates coaxial on said shank, shafts journalled on said frame betweensaid plates, an eccentric on each shaft between said plates, threadrolls journalled on said eccentrics, a pinion on each shaft, a spur gearmeshing with said pinions and splined to said shank, a torsion springconnected between said shank and said frame to urge said frame in afirst rotational direction relative to said shank, a collar axiallyslidable on said shank, a dog clutch including a first clutch part onsaid frame and a second clutch part on said collar, first and secondmating surfaces on said first and second clutch parts, respectively,holding said frame against rotation in said first rotational direction,an axially aligned reverse cutting edge drill mounted forward of saidfront plate to enter a hollow workpiece before said thread rolls act onthe external surface of said workpiece, diametrically opposed slots insaid shank, means including transverse pins extending through said slotsand connecting said drill to said collar, a coil spring in said shankacting to axially urge together said clutch parts, an axially taperedsurface on said second mating surface tapering in said first rotationaldirection, means to relatively axially separate said clutch parts as aworkpiece and said frame are relatively axially advanced to roll athread on said workpiece, whereby the tapered surface and said torsionspring establish arcuate movement of said frame in said first rotationaldirection relative to said shank to move said thread rolls transverselyaway from the axis of said rolling head to form a tapered thread on saidworkpiece, arcuate stop means on said first and second clutch parts toestablish an arcuate stop for said first and second clutch parts aftersuflicient axial separation thereof has caused said first and secondmating surfaces to become disengaged and said torsion spring has causedrapid arcuate movement of said frame to eifect a rapid opening of saidthread rolls, and said drill cutting the internal diameter of saidworkpiece cylindrical to the diameter of the drill as said workpiece andsaid frame, are relatively axially retracted.

14. A taper thread rolling head having an axis, comprising, incombination, a hollow shank adapted for mounting in a support anddisposed coaxially on said axis,

a frame including first and second plates coaxial on said shank, skewedshafts journalled on said frame between said plates, an eccentric oneach shaft between said plates, thread rolls journalled on saideccentrics, a pinion on each shaft, a spur gear meshing with saidpinions and splined to said shank, a hub on said spur gear journallingsaid frame on said shank, a spring housing as part of said frame andarcuately adjustably fastened to said second plate, a torsion springconnected between said shank and said spring housing to urge said framein a first rotational direction relative to said shank, a collar axiallyslidable on said shank, a dog clutch including a first clutch part onsaid spring housing and a second clutch part on said collar, first andsecond mating surfaces on said first and second clutch parts,respectively, holding said frame against rotation in said firstrotational direction, an axially aligned reverse cutting edge drillmounted forward of said front plate to enter a hollow workpiece beforesaid thread rolls act on the external surface of said workpiece,diametrically opposed slots in said shank, means including transversepins extending through said slots and connecting said drill to saidcollar, a coil spring in said shank acting to axially urge together saidclutch parts, an axially tapered surface on said second mating surfacetapering in said first rotational direction, means to axially separatesaid second clutch part from said first clutch part as a workpiece andsaid frame are relatively axially advanced to roll a thread on saidworkpiece, whereby the tapered surface and said torsion spring establisharcuate movement of said frame in said first rotational directionrelative to said shank to move said thread rolls transversely away fromthe axis of said rolling head to form a tapered thread on saidworkpiece, arcuate stop means on said first and second clutch parts toestablish an arcuate stop for said first and second clutch parts aftersufficient axial separation thereof has caused said first and secondmating surfaces to become disengaged and said torsion spring has causedrapid arcuate movement of said frame to effect a rapid opening of saidthread rolls, and said drill cutting the internal diameter of saidworkpiece cylindrical to the diameter of the drill as said workpiece andsaid frame are relatively axially retracted.

15. A work head having an axis, comprising, in combination, a frameadapted for mounting in a support and disposed coaxially on said axis,work dies carried on said head, a first mating part carried relative tosaid frame, a second mating part axially movable relative to said frame,first and second mating surfaces on said first and second mating parts,respectively, a profile cam surface other th an axially parallel on oneof said mating surfaces, means connecting said mating parts to said workdies to effect movement thereof relative to said axis upon relativemovement of said mating parts, means connected to rotatively urgetogether said mating surfaces, and means to relatively axially move saidmating parts as a workpiece and said frame are relatively axiallyadvanced to work said workpiece, whereby the profile cam surface andsaid urging means establish relative arcuate movement of said matingparts to move said work dies relative to the axis of said head.

16. A work head having an axis, comprising, in combination, a shankadapted for mounting in a support and disposed coaxially on said axis, aframe on said shank, eccentrics on said frame, work dies carried formovement by said eccentrics, a first mating part carried relative tosaid frame, a second mating part axially movable relative to said frame,first and second mating surfaces on said first and second mating parts,respectively, holding said frame against rotation in a first rotationaldirection, a profile cam surface other than axially parallel on one ofsaid mating surfaces, means connecting said mating parts to saideccentrics to efiect' arcuate movement of said eccentrics relative to,said frame upon relative rotational movement of said mating parts,spring means connected to axially urge together said mating parts and torotatively urge together said mating surfaces, and means to relativelyaxially move said mating parts as a workpiece and said frame arerelatively axially advanced to work said workpiece, whereby the profilecam surface and said spring means establish relative arcuate movement ofsaid mating parts to move said work dies transversely relative to theaxis of said head to form a variable diameter external surface on saidworkpiece.

References Cited in the file of this patent UNITED STATES PATENTSPaterson May 15, 1888 Hallberg Apr. 4, 1944 Chamberlain Apr. 10, 1951Erdelyi Sept. 8, 195 3 Erdelyi Oct. 18, 1955

